Electronic paper, also known as ePaper, is a new category of display that is expected to become widely used in the coming years. The display operates in a reflective mode and is bi-stable, i.e., it has two stable states. As such, the display uses low power, generally only requiring power to change the image and almost no power to maintain an image.
Because they compete with ordinary printed paper, the most common form of a display, ePaper displays must be made at low cost. Accordingly, like ordinary printed paper, ePaper needs to be made by a printing process. Specifically, the manufacturing process for producing the electronics used in ePaper displays needs to be a printing process, either on individual sheets or on a web, e.g., a roll-to-roll process. The printing speeds can be expected to be similar to those used in newspaper and magazine production except that rather than ordinary inks, electronic inks will be used to produce the electronic circuits employed in the ePaper display.
A major consequence of producing displays at high speed by printing is that a large number of displays are made in a very short time. Consequently, there needs to be a way to know if the displays are good and the process is in control. If not, a large amount of scrap will be made very quickly. It is thus critical to know the quality of the printed electronics on the press as the display is being made. The present disclosure addresses this critical need for successful adoption of ePaper displays on a widespread commercial scale.